GB2257758A

GB2257758A - Lubricated pulley assembly

Info

Publication number: GB2257758A
Application number: GB9214577A
Authority: GB
Inventors: Werner Klein; Norbert Loser; Edmund Sander
Original assignee: SKF Gleitlager GmbH
Current assignee: SKF Gleitlager GmbH
Priority date: 1991-07-16
Filing date: 1992-07-09
Publication date: 1993-01-20
Anticipated expiration: 2012-07-09
Also published as: DE4123484A1; GB2257758B; GB9214577D0

Description

1 Z 2 3 77 3 3 A PULLEY ASSEMBLY The invention relates to a pulley

assembly, particularly a high speed cable pulley assembly.

One form of pulley is already known from US 3 701 571, in which a pulley body is plain bearing mounted on a hub which is axially divided. The hub portions are connected in one piece to cover plates which are provided with radial surfaces on which the pulley body can run. Pulley and cover plates are held together by screws to form one unit.

Were a prior art pulley such as this to be used as a high speed cable pulley, e.g. for applications in the textile industry, only a relatively short effective life could be anticipated even when the sliding surfaces are suitably pre-lubricated. After displacement of the lubricant, the sliding surfaces rub on one another and in most cases the surface of the hub shell becomes damaged at places which are under stress.

One object of at least the preferred embodiment of the invention is to provide a pulley assembly with a long operative to be while ensuring that the pulley assembly is of simple and favourably priced construction.

Thus in one aspect the invention provides a pulley assembly comprising a rotor mounted on a hub and forming a plain bearing therewith, lubricant pocket means being provided in a bearing surface of the plain bearing, said pocket means extending axially of the bearing and being arranged to contain lubricant and to provide said lubricant to the bearing surface.

The lubricant pocket means may also be disposed in a bearing surface of an axially-facing plain bearing formed by the rotor and the hub.

In a further aspect the invention provides a pulley assembly comprising a rotor mounted on a hub and forming a plain bearing therewith, means providing further surfaces extending radially outwardly of the hub to form further axially-facing plain bearings with side surfaces of the rotor, and a plurality of lubricant pockets angularly spaced apart around the bearing surface of the hub and extending axially thereof, said pockets also extending radially in said further surfaces to lubricate the axially facing bearings.

Thus, in this embodiment the object is achieved by lubricant cups distributed over the periphery, machined into the shell of the hub and extending substantially axially therein, being continued radially in the cover plates, in the region of the side faces of the pulley body.

The lubricant pockets distributed over the periphery constitute grease storage-means for the sliding surfaces situated between them. By the continuation into the cover plates, there is a constantly renewing lubrication on all sliding surfaces of the axially and radially guided pulley body. By the provision of a plurality of distributed lubricant pockets over the periphery, there remain in relation to the total sliding surface relatively smaller intermediate sliding portions which receive grease from the lubricant pocket situated in front of them in the direction of rotation. This has the advantage of good grease distribution over the entire periphery. The radial portions of the lubricant pockets can in principle be constructed with a smaller storage volume since by virtue of the rotary movement, the grease contained in them has a tendency to move radially outwardly and to draw grease out of the lubricant pocket in the hub.

1 According to a further feature of the invention, the radial expansion of the portions of the lubricant pockets extending in the cover plates is less than the diameter of the effective working surface for the pulley body. Thus, the lubricant pockets are covered by the pulley body. Grease is not able to emerge freely and during operation it is delivered only to the sliding surfaces.

In the case of one preferred embodiment, the width of the lubricant pockets in a peripheral direction is less than one-fifth of the sliding surfaces disposed between the lubricant pockets. In development testing, this sub-division has proved successful, the size of the lubricant pockets in proportion to the sliding surfaces which are to be lubricated being such as to provide adequate finely dispensed lubrication as required for a long effective life.

The invention will be described in detail hereinafter with reference to an example shown in the accompanying drawings in which:

Fig. 1 is a partial longitudinal section through a cable pulley with lubricant pockets, and Fig. 2 shows a cross-section through the cable pulley according to Fig. 1, taken on the line AA.

The cable pulley shown in the drawings consists of two cover plates 1, 2 and a pulley body 3. The (according to Fig. 1).lower cover plate 2 is provided with an integrally formed hub 4. The upper cover plate 1 has a press button-shaped snap-action locking means 5 which co-operates with a matching bore in the hub 4 to fix both cover plates 1, 2 radially and axially. The outer surface of the hub forms a sliding surface 6 for the pulley body 3 which is rotatable thereon. Both cover plates 1, 2 are provided with annular recesses 7 which form working surfaces 8 for the pulley body 3 Machined into the outer surface of the hub 4 and distributed over the periphery are five axially extending lubricant pockets 9. They continue by means of radially extending portions 10 which are let into the working surface 8 of the cover plates 1, 2. The radial expansion of these portions 10 extends only over a part of the lateral faces 11 of the pulley body 3. Thus, the lubricant pockets 9 encircling the pulley bodY 3 in a U-shape are masked except for the clearance necessary for free rotation. The width of the lubricant pockets 9 in a peripheral direction amounts to approx. one-fifth of the portions 12 of sliding surface disposed between them.

Claims

1. A pulley assembly comprising a rotor mounted on a hub and forming a plain bearing therewith, lubricant pocket means being provided in a bearing surface of the plain bearing, said pocket means extending axially of the bearing and being arranged to contain lubricant and to provide said lubricant to the bearing surface.

2. A pulley assembly according to claim 1, the lubricant pocket means also being disposed in a bearing surface of an axially-facing plain bearing formed by the rotor and the hub.

3. A pulley assembly comprising a rotor mounted on a hub and forming a plain bearing therewith, means providing further surfaces extending radially outwardly of the hub to form further axially-facing plain bearings with side surfaces of the rotor, and a plurality of lubricant pockets angularly spaced apart around the bearing surface of the hub and extending axially thereof, said pockets also extending radially in said further surfaces to lubricate the axially facing bearings.

4. A pulley assembly according to claim 3, wherein the further surfaces are provided by cover plates on both sides of the rotor.

5. A pulley assembly according to claim 3 or claim 4, wherein the radial extent of the lubricant pockets in the further surfaces is less than the radial extent of the axially-facing plain bearings.

6. A pulley assembly according to any of claims 3, 4 or 5, wherein the peripheral extent of the lubricant pockets is less than one-fifth of bearing surfaces of the hub disposed between them.

7. A pulley assembly according to any preceding claims, being a cable pulley assembly.

8. A pulley assembly substantially as herein described with reference to and as shown in the accompanying drawings.